01
The Engine
Cardiorespiratory
O₂
How well your heart and lungs deliver oxygen to working muscle. The ceiling on performance today and on how long you stay capable.
Vital Capacity
Clinical medicine, organized around how you train.
Vital Capacity is a performance medicine practice for adults who train seriously. The model is simple: one physician reads your labs, fitness, strength, body composition and recovery as one picture, and owns what happens next.
Or take the Capacity Quiz: 11 questions, a profile of your own answers.
Built by Andrew Irwin, MD, CSCS. In development and not accepting patients.
The gap
Two halves of the same body.
Fit adults get medical care from people who don't understand training, and training advice from people who can't practice medicine.
So the physical comes back normal while the things holding people back sit in tests nobody ordered: a heart-disease marker climbing in the background, early insulin trouble, a fitness number lower than it should be, muscle disappearing behind a stable weight. Vital Capacity is built to close that gap.
The model
Five systems, read as one picture.
A longer, healthier life depends on five connected systems. Most care looks at one at a time. The model maps all five with one physician and names the one limiting you now.
02
The Fuel System
Metabolic
GLU
Glucose, insulin, and where fat is stored. The system behind most preventable disease over the next thirty years.
03
Load Tolerance
Musculoskeletal
LOAD
Whether your body can carry the load you put on it. What decides if you stay strong and mobile into your eighties.
04
The Infrastructure
Vascular
FLOW
The long-term trajectory of your heart and arteries, independent of how you feel today. The system most often caught too late.
05
Regulation
Recovery
REST
Whether you're adapting to the load, or breaking down quietly while the numbers still look fine.
Sample case · composite for illustration
A normal physical. A hidden ceiling.
Five Ironman finishes, a VO₂ max in the top 5% for his age, and eighteen months of getting slower. His annual physical came back normal and missed what mattered.
Vital Capacity Arc Report
Elite fitness, hidden metabolic risk
Composite
M.K. / 47 / C-suite
VO2 max
58
mL/kg/min
top 5% for age
ApoB
98
mg/dL
above goal
Lp(a)
150
nmol/L
above threshold
Fasting insulin
14
µIU/mL
above target
Primary bottleneck
Cardio is elite. Metabolism isn't keeping up.
Founder
Andrew Irwin, MD, CSCS
Internal medicine physician. Certified Strength and Conditioning Specialist. Ironman and Hyrox competitor.
I have worked in Himalayan villages with no internet and no backup, and cared for patients whose bodies were too weak to tolerate the treatments meant to save them. Vital Capacity is the medical relationship I think serious adults should have: one physician who understands the training, makes the clinical decisions, and follows what happens over decades.
Writing
The thinking behind the practice, in public.
Longer essays on Substack, shorter clinical notes on LinkedIn.
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